Mike

I'm looking at DME/KLR manual and the Porsche Service manuals and notice that there seem to be only two active wires (plus a common) for the injectors - one is marked, "Injectors 1+2" and the other, "Injectors 3+4".

To me this means that the #1 and #2 injectors fire together.

Am I reading this right? Can someone explain to me the reason Porsche (or anyone else) would want to squirt fuel into a cylinder during what I think is its exhaust stroke?


Thanks.

keith

cooling, right?

Mike

I thought about cooling, but didn't think they would simply squirt raw fuel in if it were just going to be vented to the atmosphere. I'm guessing there's an aspect of the overall valve timing that might mean this isn't what's happening...

924SBob

I'm not sure about the wiring logic, but I have read that the injector does squirt onto a closed intake valve, logical while the piston is on it's exhaust stroke.

art

When the injector fires on the second time, it is putting fuel into a hot area which will vaporize and help cumbustion. Also I think that there may be not enough time for a full atomized/vaporized squirt to happen all at once. I have an aftermarket injection system on a 911 that fires 3 injectors at once, which would mean that each cylinder gets multiple 'shots' per intake cycle. In this sytem I think the injectors are continuously firing because the programmer has an output showing duty cycle. This would mean that the timing of the injections is less important than having a ready supply of atomized fuel in the manifold.

Art